Revenue - Summary of Revenues by End-Use Markets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total net sales	$ 690.1	$ 489.0	$ 1,792.1	$ 1,272.6
Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	603.4	418.0	1,546.6	1,080.7
Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	115.1	88.4	315.1	248.7
Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(28.4)	(17.4)	(69.6)	(56.8)
Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	344.2	206.1	885.9	540.7
Aerospace and Defense | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	321.6	191.4	832.1	504.4
Aerospace and Defense | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	31.2	20.1	75.0	55.9
Aerospace and Defense | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(8.6)	(5.4)	(21.2)	(19.6)
Medical
Disaggregation of Revenue [Line Items]
Total net sales	86.2	54.2	219.1	144.0
Medical | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	63.9	40.5	154.2	104.1
Medical | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	32.8	19.6	90.3	56.2
Medical | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(10.5)	(5.9)	(25.4)	(16.3)
Transportation
Disaggregation of Revenue [Line Items]
Total net sales	52.8	46.4	131.1	126.2
Transportation | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	51.2	45.5	127.2	122.9
Transportation | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	1.8	1.0	4.6	3.5
Transportation | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.2)	(0.1)	(0.7)	(0.2)
Energy
Disaggregation of Revenue [Line Items]
Total net sales	46.6	34.7	109.4	80.0
Energy | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	42.8	32.9	101.4	74.7
Energy | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	3.9	1.8	7.9	5.4
Energy | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.1)	0.0	0.1	(0.1)
Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	130.7	114.3	355.3	291.3
Industrial and Consumer | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	123.9	107.7	331.7	274.6
Industrial and Consumer | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	15.8	12.5	45.9	37.3
Industrial and Consumer | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(9.0)	(5.9)	(22.3)	(20.6)
Distribution
Disaggregation of Revenue [Line Items]
Total net sales	29.6	33.3	91.3	90.4
Distribution | Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.0	0.0
Distribution | Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	29.6	33.4	91.4	90.4
Distribution | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	$ 0.0	$ (0.1)	$ (0.1)	$ 0.0